// Copyright 2017 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
////////////////////////////////////////////////////////////////////////////////

package com.google.crypto.tink.subtle;

import java.nio.ByteBuffer;
import java.security.GeneralSecurityException;

/**
 * StreamSegmentDecrypter is a helper class that decrypts individual segments of a stream.
 *
 * <p>Instances of this interfaces are passed to {@link StreamingAeadDecryptingChannel}. Each
 * instance must be initialized with the header of the ciphertext.
 *
 * @since 1.1.0
 */
public interface StreamSegmentDecrypter {
  void init(ByteBuffer header, byte[] aad) throws GeneralSecurityException;

  /**
   * Decrypts a ciphetext segment.
   *
   * @param segmentNr the number of the segment
   * @param isLastSegment true if this segment is the last segment of the ciphertext stream. The
   *     last segment is encrypted (or authenticated) differently to detect truncated ciphertext.
   * @param plaintext the decrypted plaintext.
   * @throws GeneralSecurityException if ciphertext was not a valid ciphertext for the given
   *     segment.
   */
  void decryptSegment(
      ByteBuffer ciphertext, int segmentNr, boolean isLastSegment, ByteBuffer plaintext)
      throws GeneralSecurityException;
}
